Clinical and Neurophysiological Outcomes after Cryotherapy in Ankle Joint Injured Patients

Despite the fact that cryotherapy is the standard of care for acute and subacute injuries, its physiological mechanisms of action are not well understood. Cryotherapy may have therapeutic effects after injury, but the benefits may be limited to pain relief in the early states of rehabilitation. The overall purpose of this study was to evaluate the effects of focal joint cooling on self-reported pain and neurophysiological function of the sural sensory nerve and the spinal reflex excitability of the soleus and fibularis longus motor neuron pools. In manuscript 1, we concluded that patients who were experiencing mild pain due to lateral ankle sprains had lower amplitude and slower conduction velocity of the sural nerve at baseline compared to healthy participants. Focal ankle joint cooling altered all portions of the sensory nerve action potential measurements, but did not result any differences between groups. The results of manuscript 2 indicate that although pain may be a causal factor in arthrogenic muscle inhibition, relief of pain due to a short duration focal joint cooling does not cause a subsequent modulation or facilitation of lower extremity motor neuron pools. Lastly, in manuscript 3, we saw that participants who experienced a meaningful decrease in pain after focal joint cooling were more likely to have an increase in sensory nerve action potential amplitude and an abnormal nerve conduction velocity. Clinicians still have few evidence-based guidelines to prescribe an optimal cryotherapy intervention, but the results of this study allow clinicians and researchers to better understand the effects of cryotherapy on sensory and mixed motor nerves, and the relationship between altered nerve responses and pain control. We recommend short duration cryotherapy interventions for pain relief after subacute ankle joint injury, but cannot recommend cryotherapy for motor neuron pool facilitation in a subacute, painful joint injured population at this time. Department of Human Services Curry School of Education University of Virginia Charlottesville, Virginia APPROVAL OF THE DISSERTATION This dissertation, "Clinical and Neurophysiological Outcomes after Cryotherapy in Ankle Joint Injured Patients" has been approved by the Graduate Faculty of the Curry School of Education in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

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